Having been to my first REI garage sale recently, and being shocked at appalled at the state of people's returns, I can say I wouldn't be surprised. Here I am doing my best to use something maybe once or twice before deciding on whether or not to return it, and feeling like I'm some sort of mooch in the process. Meanwhile I saw more totally abused and destroyed stuff than I can shake a stick at, often a couple years old. Moreover, I've heard tales from several employees of people openly talking about how they take advantage of the system; the best/worst being a woman who openly said "this is great, I'll bring my kids' clothes back as they outgrow them, and get them new stuff!"
If they wanted to shorten the policy to something more like, a couple months, or even a month, I'd be pleased enough to continue buying my stuff there honestly. If they decided to get rid of the ability to return it even gently used I would stop buying my stuff there however, because ultimately it's the biggest draw to using REI over online sites where the prices might well be much cheaper.